Particularly with deep oil wells, a certain amount of sand and other debris is carried through the down-well valves, and may lodge in and disable the pumping action of the travelling valve mechanism manipulated by pump rods from a top side pumping mechanism. If the travelling valve does not close properly because of interspersed debris it cannot lift the fluids as the pumping mechanism lifts the rods.
Present practice is to withdraw the down-hole pump or valve assembly and rods with a hoist and derrick to clean the pump valve. This is time consuming, costly and requires expensive heavy duty equipment.
Well cleaning has been proposed by U.S. Pat. No. 1,075,261 by pumping down-hole through special pipes a fluid under pressure to break up or dislodge debris. However, this requires expensive pipe installation, and may not be compatible in deep wells or in oil wells having limited casing space, even if the expense were warranted.